Expandable fusion device and method of installation thereof

ABSTRACT

Expandable fusion devices capable of being inserted between adjacent vertebrae to facilitate the fusion process. The expandable fusion device may include first and second endplates, a translation member configured to expand an anterior side and/or posterior side of the device, a plurality of joists configured to connect the first and second endplates to the translation member, and first and second actuation members disposed internally to the device such that openings on a back side of the device can be used to expand or compress the anterior side, the posterior side, or both and such openings may also be used to introduce graft material into the device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part application of U.S. patentapplication Ser. No. 16/991,303 filed on Aug. 12, 2020, which is acontinuation in part application of U.S. patent application Ser. No.15/196,231 filed on Jun. 29, 2016, the contents of all of which areincorporated by reference herein in their entireties for all purposes.

FIELD OF THE INVENTION

The present invention relates to the apparatus and method for promotingan intervertebral fusion, and more particularly relates to an expandablefusion device capable of being inserted between adjacent vertebrae tofacilitate the fusion process.

BACKGROUND

A common procedure for handling pain associated with intervertebraldiscs that have become degenerated due to various factors such as traumaor aging is the use of intervertebral fusion devices for fusing one ormore adjacent vertebral bodies. Generally, to fuse the adjacentvertebral bodies, the intervertebral disc may first be partially orfully removed. Typically, an intervertebral fusion device may then beinserted between neighboring vertebrae to maintain normal disc spacingand restore spinal stability, thereby facilitating an intervertebralfusion.

There are a number of known conventional fusion devices andmethodologies in the art for accomplishing the intervertebral fusion.These include screw and rod arrangements, solid bone implants, andfusion devices which include a cage or other implant mechanism which,typically, is packed with bone and/or bone growth inducing substances.These devices are implanted between adjacent vertebral bodies in orderto fuse the vertebral bodies together, alleviating the associated pain.

However, there are drawbacks associated with the known conventionalfusion devices and methodologies. For example, two important factors inintervertebral fusion may be the anterior (lordotic) angle adjustmentand posterior height adjustment. The lordotic angle may be important inrestoring sagittal balance while the posterior height may aid inrestoring disc height and indirect decompression of the neural foramen.While convention fusion devices may allow for in-situ expansion, they donot allow for the lordotic angle and posterior height to be adjustedin-situ independently of one another.

SUMMARY

In an exemplary embodiment, the present disclosure provides anexpandable fusion device comprising a first endplate, a second endplate,a first joist and a second joist connected to the first endplate, athird joist and a fourth joist connected to the second endplate, atranslation member in engagement with the first joist, second joist,third joist, and fourth joist, and a first actuation member inengagement with the translation member assembly. The first actuationmember may be configured to move the first joist and the third joistsuch that the first endplate and the second endplate move in a directionaway from the translation member on a first side of the expandablefusion device. The expandable fusion device may also include a secondactuation member in engagement with the translation member assembly,wherein the second actuation member is configured to move the secondjoist and the fourth joist such that the first endplate and the secondendplate move in a direction away from the translation member on asecond side of the expandable fusion device.

In an exemplary embodiment, an expandable fusion device comprising afirst endplate, a second endplate, a translation member disposed atleast partially between the first endplate and the second endplate,wherein the translation member assembly comprises an anteriortranslation component disposed on an anterior side of the expandablefusion device, the anterior translation portion comprises an anteriorbore. The expandable fusion device may also include a posteriortranslation component disposed on a posterior side of the expandablefusion device, wherein the posterior translation portion comprises aposterior bore. The translation member may be configured to expand thefusion device on an anterior side by moving an anterior side of thefirst endplate and an anterior side of the second endplate and thetranslation member may be configured to expand the fusion device on aposterior side by moving a posterior side of the first endplate and aposterior side of the second endplate. The first endplate may be engagedwith the translation member via a first joist and a second joist, andwherein the second endplate is engaged with the translation member via athird joist and a fourth joist.

In an exemplary embodiment, an expandable fusion device includes firstand second endplates, a plurality of moveable joists engaged with thefirst and second endplates, a translation member assembly including anactuation member and a plurality of ramps engaged with the plurality ofjoists, and a locking washer keyed to the actuation member. Theactuation member is configured to move the joists such that the firstand second endplates move away from one another, and the locking washeris configured to prevent rotation of the actuation member, therebylocking a height and lordosis of the first and second endplates. Theactuation member may include a head and a threaded shaft extending alonga central longitudinal axis that terminates at a distal end. Thetranslation member assembly may include a translation component defininga first through bore and a front ramp defining a second through bore,wherein the head of the actuation member is receivable through the firstbore in the translation component and the shaft is receivable throughthe second bore in the front ramp. The head may define a plurality ofprotrusions with gaps therebetween extending radially around the headand a channel below the protrusions. When inserting a driver to rotatethe actuation member, the locking washer may be pulled aside, releasingthe actuation member to rotate freely, and removing the driver may allowthe locking washer to key into the protrusions on the head, therebylimiting rotation of the actuation member. The locking washer mayinclude a full ring connected to a partial ring by an arm, wherein thefull ring is configured to rest against a top of the head, the partialring is configured to seat in the channel, and the arm is configured tofit within one of the gaps between the protrusions along the head. Thearm may form a projection from an outer periphery of the full ring,wherein the projection is configured to interface with an implant keydefining a recess and a tab configured to engage with the projection.The full ring may have an asymmetric face configured to cover the top ofthe head.

In an exemplary embodiment, an expandable fusion device includes firstand second endplates, first and second joists engaged with the firstendplate, third and fourth joists engaged with the second endplate, atranslation member in engagement with the first, second, third, andfourth joists, a first actuation member in engagement with thetranslation member, wherein the first actuation member is configured tomove the first and third joists to expand the first and second endplateson a first side of the expandable fusion device, a first locking washerattached to the first actuation member, wherein the first locking washeris configured to prevent rotation of the first actuation member, asecond actuation member in engagement with the translation memberassembly, wherein the second actuation member is configured to move thesecond and fourth joists to expand the first and second endplates on asecond side of the expandable fusion device, and a second locking washerattached to the second actuation member, wherein the second lockingwasher is configured to prevent rotation of the second actuation member.The first side may be an anterior side and the second side may be aposterior side such that the first actuation member expands the anteriorside while the second actuation member expands the posterior side. Thefirst and second endplates may be configured to pivot on top of therespective joists. For example, one of the joists may include a pocketconfigured to receive a tab disposed on the first or second endplate,and another joist may include a cylindrical bore configured to receive acylindrical stem disposed on an opposite side of the first or secondendplate. The cylindrical stem may be hollow and may extend from a fronttoward a back of the first or second endplate. One or both of the firstand second endplates may be 3D printed with a surface pattern andbi-directional teeth configured to promote bone growth. For example, thesurface pattern may be an open hexagonal pattern, an open parallel strutpattern, or the pattern may be filled with a porous lattice structure.

In an exemplary embodiment, a system for installing and/or expanding anexpandable fusion device includes an expandable fusion device and aninstrument for installing and/or expanding the expandable fusion device.The expandable fusion device includes first and second endplates, atranslation member assembly disposed at least partially between thefirst and second endplates, wherein the translation member assemblycomprises: an anterior translation component disposed on an anteriorside of the expandable fusion device including an anterior back rampwith a first through bore; an anterior actuation member including a headand a threaded shaft for moving the anterior translation component; aposterior translation component disposed on a posterior side of theexpandable fusion device including a posterior back ramp with a secondthrough bore; and a posterior actuation member including a head and athreaded shaft for moving the posterior translation component, whereinrotation of the anterior and/or posterior actuation members isconfigured to expand the fusion device on the anterior side and/orposterior side, respectively, to achieve a height and lordosis of thefirst and second endplates. The instrument for installing and/orexpanding the expandable fusion device includes a body with a cannulatedsleeve attachable to one of the first and second through bores, a firstdriver positionable through the cannulated sleeve, the first driverhaving a tip configured to engage with a drive recess in the head of theanterior or posterior actuation member, and a second driver having a tipconfigured to engage with a drive recess in the head of the otheractuation member. A distal end of the body may include a pair of tabsconfigured to interface with corresponding instrument notches onopposite sides of the anterior and posterior back ramps. The first andsecond drivers may be aligned in parallel. The first or second throughbore may be internally threaded and the cannulated sleeve may have athreaded end configured to mate with the internally threaded bore of theanterior or posterior back ramp.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a side view of an embodiment of an expandable fusion deviceshown between adjacent vertebrae according to the present disclosure.

FIG. 2 is a perspective view of an embodiment of an expandable fusiondevice according to the present disclosure.

FIG. 3 is an end view of an embodiment of the expandable fusion deviceof FIG. 2.

FIG. 4 is end view of an embodiment of an endplate of the expandablefusion device of FIG. 2 showing a pivot point.

FIG. 5 is another end view of an embodiment of an endplate of theexpandable fusion device of FIG. 2 showing a pivot point.

FIG. 6 is a perspective view of an embodiment of a translation memberassembly of the expandable fusion device of FIG. 2.

FIG. 7 is a perspective view of an expansion fusion device according toanother embodiment of the present disclosure.

FIG. 8 is another view of an embodiment of the expandable fusion deviceof FIG. 7.

FIG. 9 is an end view of an embodiment of the expandable fusion deviceof FIG. 7.

FIG. 10 is a top view of an embodiment of the expandable fusion deviceof FIG. 7.

FIG. 11 illustrate an expandable fusion device according to anotherembodiment of the present disclosure.

FIG. 12 illustrate an expandable fusion device according to anotherembodiment of the present disclosure.

FIG. 13 illustrates an expandable fusion device according to anotherembodiment of the present disclosure.

FIG. 14 is a cross-sectional view of the expandable fusion device ofFIG. 13 taken along line a-a.

FIG. 15 is a cross-sectional view of the expandable fusion device ofFIG. 13 taken along line b-b

FIG. 16A and 16B are end views of an embodiment of an endplate of theexpandable fusion device of FIG. 13 showing a pivot point.

FIG. 17 is a close-up view of an embodiment the endplate of FIGS. 16Aand 16B taken along circle 17.

FIG. 18 is a side view of an embodiment of the endplate of FIG. 16showing contact with a ramped translation member.

FIG. 19 is an end view of an expandable fusion device according toanother embodiment of the present disclosure.

FIG. 20 is a cross-sectional view of the expandable fusion device ofFIG. 19 taken along line c-c.

FIG. 21 is a cross-sectional view of the expandable fusion device ofFIG. 20 taken along line d-d.

FIGS. 22 and 23 are end views of an expandable fusion device accordingto another embodiment of the present disclosure.

FIGS. 24 and 25 are end views of an expandable fusion device accordingto another embodiment of the present disclosure.

FIG. 26 is a perspective view of a translation member assembly in theform of translating bar according to another embodiment of the presentdisclosure.

FIGS. 27-29 illustrate end views of a translation member assembly thatincorporates side wedges according to another embodiment of the presentdisclosure.

FIGS. 30-33 illustrate a corpectomy device according to anotherembodiment of the present disclosure.

FIGS. 34 and 35 illustrate another technique for expansion of anexpandable fusion device according to the present disclosure.

FIGS. 36 and 37 illustrate another technique for expansion of anexpandable fusion device according to the present disclosure.

FIGS. 38 and 39 illustrate another technique for expansion of anexpandable fusion device according to the present disclosure.

FIG. 40 illustrates a perspective view an expandable fusion deviceaccording to another embodiment of the present disclosure.

FIG. 41 illustrates a perspective view an expandable fusion deviceaccording to another embodiment of the present disclosure.

FIG. 42 is a cross-sectional view of an embodiment of the expandablefusion device of FIG. 41 taken along plane 42.

FIGS. 43-45 illustrate embodiments for expansion of the expandablefusion device of FIG. 41.

FIG. 46 is a cross-sectional view of an expandable fusion deviceaccording to another embodiment of the present disclosure.

FIGS. 47-49 illustrate another technique for expansion of an expandablefusion device according to the present disclosure.

FIGS. 50-54 illustrate another technique for expansion of an expandablefusion device according to the present disclosure.

FIGS. 55A-55D illustrate perspective views of an exemplary expandablefusion device in various states of expansion according to an embodimentof the present disclosure.

FIGS. 56A-56D illustrate an end view of an exemplary expandable fusiondevice in various states of expansion according to an embodiment of thepresent disclosure.

FIGS. 57A and 57B illustrate perspective view of an exemplary expandablefusion device in a state of expansion according to an embodiment of thepresent disclosure.

FIGS. 58A and 58B illustrate perspective views of an exemplarytranslation member for an expandable fusion device according to anembodiment of the present disclosure.

FIG. 59 illustrates a perspective view of an exemplary translationmember and joists for an expandable fusion device according to anembodiment of the present disclosure.

FIGS. 60A and 60B illustrate perspective views of two exemplaryembodiments of a joist for an expandable fusion device.

FIG. 61A illustrates perspective views of an exemplary endplate for anexpandable fusion device according to an embodiment of the presentdisclosure.

FIG. 61B illustrates a perspective view of an exemplary endplate andexemplary joists for an expandable fusion device according to anembodiment of the present disclosure.

FIGS. 62A-62B illustrate perspective views of an exemplary locking stemfor an expandable fusion device according to an embodiment of thepresent disclosure.

FIG. 62C illustrates a perspective view of an exemplary translationmember for an expandable fusion device according to an embodiment of thepresent disclosure.

FIG. 63 illustrates a perspective view of an exemplary translationmember for an expandable fusion device according to an embodiment of thepresent disclosure.

FIG. 64A-64B illustrate front views of the implant in a collapsedposition and partially expanded to an arbitrary angle, respectively,according to one embodiment.

FIGS. 65A-65B illustrate perspective views of the front and rear rampswith the addition of joists, respectively, according to one embodiment.

FIGS. 66A-66B illustrate perspective and top views, respectively, of theanterior and posterior actuation members for controlling movementbetween the front and back ramps, thereby resulting in expansion of theendplates.

FIGS. 67A-67D illustrate one endplate and joists, thereby allowing theendplates to pivot on top of the joists according to one embodiment.

FIGS. 68A-68B illustrate front and back isometric views, respectively,of an expanded implant according to one embodiment.

FIGS. 69A-69D illustrate perspective and front views of the actuationmembers with a locking washer for locking rotation according to oneembodiment.

FIGS. 70A-70B illustrate an instrument for inserting and/or expandingthe implant according to one embodiment.

FIGS. 71A-71C illustrate perspective, top, and side views, respectively,of an embodiment of the endplates with a hexagon pattern formed bythree-dimensional printing.

FIGS. 72A-72C illustrate perspective, top, and side views, respectively,of an embodiment of the endplates with a strut pattern formed bythree-dimensional printing.

FIG. 73 illustrates alternative embodiments of endplates with teethand/or a filled porous structure.

DETAILED DESCRIPTION

The following description of certain embodiment(s) is merely exemplaryin nature and is in no way intended to limit the invention, itsapplication, or uses.

A spinal fusion is typically employed to eliminate pain caused by themotion of degenerated disc material. Upon successful fusion, a fusiondevice becomes permanently fixed within the intervertebral disc space.Looking at FIG. 1, an exemplary embodiment of an expandable fusiondevice 10 is shown between adjacent vertebral bodies 15 and 20. Theexpandable fusion device 10 may be implanted between two adjacentvertebral bodies 15 and 20 in any section of the spine, including thecervical, thoracic, lumbar, and sacral vertebral sections. More than oneexpandable fusion device 10 may be implanted within the body, forexample, between successive or separated vertebrae. As illustrated, theexpandable fusion device 10 engages the endplates 25 and 30 of theadjacent vertebral bodies 15 and 20 and, in the installed position,maintains normal intervertebral disc spacing and restores spinalstability, thereby facilitating an intervertebral fusion. The expandablefusion device 10 can be manufactured from a number of materialsincluding titanium, stainless steel, titanium alloys, non-titaniummetallic alloys, polymeric materials, plastics, plastic composites,PEEK, ceramic, and elastic materials. In an embodiment, the expandablefusion device 10 can be configured to be placed down an endoscopic tubeand into the disc space between the adjacent vertebral bodies 15 and 20.

As illustrated, the expandable fusion device 10 may have an anteriorside 35 and a posterior side 40. As will be discussed in more detailbelow, expansion of the expandable fusion device 10 may be controlled sothat the anterior height H_(a) and the posterior height H_(p) may beindependently controlled. By way of example, the expandable fusiondevice 10 may have independent anterior expansion and posteriorexpansion mechanisms. By separate control of anterior expansion andposterior expansion, an operator may adjust the expandable fusion device10 to provide a desired amount of posterior height H_(p) and lordoticangle θ. Those of ordinary skill in the art will appreciate that thelordotic angle θ is dependent on the anterior height H_(a) and posteriorheight H_(p) of the expandable fusion device 10. In some embodiments,expansion on the anterior side 35 and the posterior side 40 may also beperformed simultaneously to maintain a lordotic angle θ with onlychanging the anterior height H_(a) and the posterior height H_(p) at thesame rate. While the expandable fusion device 10 is described hereinusing several varying embodiments, the expandable fusion device 10should not be limited to these embodiments.

In some embodiments, the expandable fusion device 10 may be configuredand sized to be placed down an insertion tube and into the disc spacebetween the adjacent vertebral bodies 15 and 20. For example, expandablefusion device 10 may be configured for insertion through an insertiontube, such as, e.g., a cannula. It should be noted, however, that theinsertion tube may alternatively have any suitable diameter. In oneembodiment, expandable fusion device 10 may be inserted through acannula having a diameter of about 8.5 mm. In some embodiments, theexpandable fusion device 10 may have a width in a range of from about 8mm to about 26 mm, and a length in a range from about 20 mm to about 65mm, or may have other suitable dimensions. Expandable fusion device 10may be inserted into a patient via a direct lateral procedure, althoughanterior, anterolateral, posterolateral or posterior proceduresalternatively may be utilized.

Expandable fusion device 10 may have an anterior height H_(a) andposterior height H_(p) that are independently adjustable. In someembodiments, the anterior height H_(a) and posterior height H_(p) mayeach be independently expanded to a height that is equal to or greaterthan about 150% of their respective initial heights. In one embodiment,the anterior height H_(a) and posterior height H_(p) may each beindependently expanded to a height that is equal to or greater thanabout 200% of their respective initial heights, or another suitablepercentage of their respective initial height.

In some embodiments, bone graft or similar bone growth inducing materialcan be introduced around and within the expandable fusion device 10 tofurther promote and facilitate the intervertebral fusion. The expandablefusion device 10, in one embodiment, may be packed with bone graft orsimilar bone growth inducing material to promote the growth of bonethrough and around the expandable fusion device 10. Such bone graft maybe packed between the endplates of the adjacent vertebral bodies 15 and20 prior to, subsequent to, or during implantation of the expandablefusion device 10.

In some embodiments, the expandable fusion device 10 may be treated witha titanium and/or hydroxyapatite plasma spray coating to encourage bonyon-growth, improving the strength and stability of the connectionbetween the respective component and the underlying bone (e.g., avertebral body). Any other suitable coating also may be provided onexpandable fusion device 10. Such coatings may include therapeuticagents, if desired. Expandable fusion device 10 also may includeradiopaque markings to facilitate in vivo visualization. In someembodiments, portions of expandable fusion device 10 may be formed of aradiolucent material, while other portions of expandable fusion device10 may be formed of radiopaque materials to facilitate imaging of theradiopaque portions of expandable fusion device 10, such as, e.g.,actuating mechanisms, endplates, ramps, or the like.

With reference now to FIGS. 2 and 3, an embodiment of the expandablefusion device 10 is shown. In an exemplary embodiment, the expandablefusion device 10 includes a first endplate 45, a second endplate 50, anda translation member assembly 55. The expandable fusion device 10 mayalso include a plurality of ramp frames that transfer motion of thetranslation member assembly 55 to the first endplate 45 and secondendplate 50. In the illustrated embodiment, the expandable fusion device10 may comprise a first anterior ramp frame 60 for engaging the firstendplate 45 on anterior side 35. The expandable fusion device 10 mayalso comprise a second anterior ramp frame 65 for engaging the secondendplate 50 on anterior side 35. The expandable fusion device 10 mayalso comprise a first posterior ramp frame 70 for engaging the firstendplate on posterior side 40. The expandable fusion device 10 may alsocomprise a second posterior ramp frame (not shown) for engaging thesecond endplate 50 on posterior side 40. The expandable fusion device 10may also comprise an actuation member, such as first actuation screw 75,for controlling anterior height H_(a) and a second actuation member,such as second actuation screw 80, for controlling posterior heightH_(p). It should be recognized that terms anterior and posterior areused to represent anatomical locations with respect to a patient.Accordingly, the terms anterior and posterior when used with respect tothe expandable fusion device 10 should not be limited to the specificside shown, as the directions anterior and posterior may changedepending, for example, on the direction of insertion.

Expandable fusion device 10 may form a distal end 85 which may beinserted first into the patient's body, and which may be tapered tofacilitate insertion between adjacent vertebral bodies 15 and 20.Expandable fusion device 10 may also form a proximal end 90 to which aninsertion device (not shown) may be connected. Expandable fusion device10 may be inserted in a collapsed configuration that is smaller than anexpanded configuration. In the expanded configuration, the anteriorheight H_(a) and/or posterior height H_(p) has been increased.Expandable fusion device 10 may be moveable from the collapsedconfiguration to the expanded configuration.

With additional reference to FIGS. 4 and 5, the first endplate 45 willnow be described in more detail. Although the following discussionrelates to the first endplate 45, it should be understood that it alsoequally applies to the second endplate 50 as the second endplate 50 issubstantially identical to the first endplate 45 in embodiments of thepresent invention. In the illustrated embodiment, first endplate 45 maycomprise an outer surface 95 extending from distal end 85 to proximalend 90. While not illustrated, in an exemplary embodiment, the outersurface 95 may include texturing to aid in gripping the adjacentvertebral bodies. Although not limited to the following, the texturingcan include teeth, ridges, friction increasing elements, keels, orgripping or purchasing projections. First endplate 45 may also comprisean anterior endplate side 100 and a posterior endplate side 105.Anterior endplate side 100 may be disposed at anterior side 35 ofexpandable fusion device 10. Posterior endplate side 105 may be disposedat posterior side 40 of expandable fusion device 10. As best seen onFIG. 4, first endplate 45 may also comprise an inner surface 110.

First endplate 45 may engage first anterior ramp frame 60 and firstposterior ramp frame 70. First endplate 45 may include a first matingfeature 115 and a second mating feature 120. The first mating feature115 and second mating feature 120 First mating feature 115 and secondmating feature 120 may form joints with corresponding mating features125 and 130 of the first anterior ramp frame 60 and the first posteriorramp frame 70. The joints formed by engagement of first mating feature115 and second mating feature 120 with corresponding mating features 125and 130 may form pivot points to facilitate independent expansion ofanterior side 35 and posterior side 40. First mating feature 115 andsecond mating feature 120 may be balls, tongue or otherwise formedprotrusions to allow pivoting of first endplate 45 with respect to firstanterior ramp frame 60 and first posterior ramp frame 70. For example,first mating feature 115 may pivot in corresponding mating feature 125of first anterior ramp frame 60. First mating feature 115 and secondmating feature 120 may also allow sliding of first endplate 45 withrespect to first anterior ramp frame 60 and/or first posterior rampframe 70. For example, second mating feature 120 may be pivot and slidein corresponding mating feature 130 of first posterior ramp frame 70. Inthe illustrated embodiment, the first mating feature 115 and secondmating feature 120 may be in the form of a ball, tongue, or otherprotrusion that mates with corresponding mating features 125 and 130,which may be in the form of a recess, groove, or otherwise formedopening.

In some embodiments, the first endplate 45 and second endplate 50 mayfurther comprise through openings 135. Through opening 135 is shown infirst endplate 45 on FIG. 2. The through openings 135 may form anopening that extends from outer surface 95 to inner surface 110. Thethrough openings 135, in an exemplary embodiment, may be sized toreceive bone graft or similar bone growth inducing material and furtherallow the bone graft or similar bone growth inducing material to bepacked in a central opening (not shown) of the expandable fusion device10.

Turning now to FIG. 6, translation member assembly 55 will now bedescribed in more detail. In the illustrated embodiment, translationmember assembly 55 may comprise an anterior translation portion 140, aposterior translation portion 145, an anterior ramped end 150, and aposterior ramped end 155. The anterior translation portion 140 andanterior ramped end 150 may be disposed on anterior side 35 ofexpandable fusion device 10. The posterior translation portion 145 andposterior ramped end 155 may be disposed on posterior side 40 ofexpandable fusion device 10. Anterior ramped end 150 and posteriorramped end 155 may be disposed on proximal end 90 of the expandablefusion device 10. Anterior ramped end 150 and posterior ramped end 155may moveable in the direction indicated by arrows 160 and 165. Theanterior translation portion 140 and posterior translation portion 145may be moveable in the direction indicated by arrows 170 and 175. Theanterior translation portion 140, posterior translation portion 145,anterior ramped end 150, and posterior ramped end 155 may engage thecorresponding ramp frame to cause expansion of the expandable fusiondevice. For example, anterior translation portion 140 and anteriorramped end 150 may be moveable to engage first anterior ramp frame 60and second anterior ramp frame 65, thus casing first anterior ramp frame60 to push outwardly on first endplate 45 and second anterior ramp frame65 to push outwardly on second endplate 50. In this manner, anteriorside 35 of expandable fusion device may be expanded/contracted byengagement of anterior translation portion 140 and anterior ramped end150 with first anterior ramp frame 60 and second anterior ramp frame 65.By way of further example, posterior translation portion 145 andposterior ramped end 155 may be moveable to engage first posterior rampframe 70 and second posterior ramp frame, thus casing first posteriorramp frame 70 to push outwardly on first endplate 45 and secondposterior ramp frame to push outwardly on second endplate 50. In thismanner, posterior side 40 of expandable fusion device may beexpanded/contracted by engagement of posterior translation portion 145and posterior ramped end 155 with first posterior ramp frame 70 andsecond anterior ramp frame.

Anterior translation portion 140 may comprise a first end 180 and asecond end 185. As illustrated, a connecting bar 190 may extend fromfirst end 180 to second end 185. First end 180 may include a bore 195,which may be threaded, for receiving first actuation screw 75. Anteriortranslation portion 140 may further comprise one or more ramps, such asramps 200, 205, 210, that are configured to engage first anterior rampframe 60 and second anterior ramp frame 65 and transfer movement of theanterior translation portion 140 thereto. Ramp 200 may be disposed atfirst end 180, ramp 205 may be disposed on connecting bar 190, and ramp210 may be disposed on second end 185.

Posterior translation portion 145 may comprise a first end 215 and asecond end 220. As illustrated, a connecting bar 226 may extend fromfirst end 215 to second end 220. First end 215 may include a bore 225,which may be threaded, for receiving second actuation screw 80.Posterior translation portion 145 may further comprise one or moreramps, such as ramps 230, 235, 240 that are configured to engage firstposterior ramp frame 70 and second posterior ramp frame and transfermovement of the posterior translation portion 145 thereto. Ramp 230 maybe disposed at first end 215, ramp 235 may be disposed on connecting bar226, and ramp 240 may be disposed on second end 220.

Anterior translation portion 140 may engage posterior translationportion 145. In some embodiments, anterior translation portion 140 mayslidingly engage posterior translation portion 145, for example, with adovetail or other suitable sliding joint. As illustrated, anteriortranslation portion 140 may comprise a flange 245 or other suitableprotrusion at second end 185 that may be received in a slot 250 atsecond end 220 of posterior translation portion 145. The flange 245 mayhave an enlarged edge (not shown) to prevent removal of flange 245 fromslot. As further illustrated, anterior translation portion 140 mayfurther comprise a protrusion 255 (e.g., tongue) at first end 180. Theflange 245 and slot 250 may form a sliding and interlocking joint thatallows translation of the anterior translation portion 140 and theposterior translation portion 145 with respect to one another. that maybe received in a groove 260 at first end 215 of posterior translationportion 145. The protrusion 255 and groove 260 may form a sliding andinterlocking joint that also allows translation of the anteriortranslation portion 140 and the posterior translation portion 145 withrespect to one another.

Anterior ramped end 150 may comprise a body portion 265. Body portion265 may comprise ramp 270 and bore 275. Ramp 270 may be configured toengage first anterior ramp frame 60 and second anterior ramp frame 65and transfer movement of the anterior ramped end 150 thereto. Bore 275may be threaded for receiving first actuation screw 75. Anterior rampedend 150 may be coupled to anterior translation portion 140 via firstactuation screw 75.

Posterior ramped end 155 may comprise a body portion 280, which maycomprise ramp 285 and bore 290. Ramp 285 may be configured to engagefirst posterior ramp frame 70 and second anterior ramp frame andtransfer movement of the posterior ramped end 155 thereto. Bore 290 maybe threaded for receiving second actuation screw 80. Posterior rampedend 155 may be coupled to posterior translation portion 145 via secondactuation screw 80. Posterior ramped end 155 may engage anterior rampedend 150, for example, via a sliding connection, such as dovetailconnection 295.

A method of installing the expandable fusion device 10 of FIGS. 1-6 isnow discussed in accordance with exemplary embodiments. Prior toinsertion of the expandable fusion device 10, the intervertebral spacemay be prepared. In one method of installation, a discectomy may beperformed where the intervertebral disc, in its entirety, is removed.Alternatively, only a portion of the intervertebral disc can be removed.The endplates of the adjacent vertebral bodies 15 and 20 may then bescraped to create an exposed end surface for facilitating bone growthacross the intervertebral space. One or more endoscopic tubes may thenbe inserted into the disc space. The expandable fusion device 10 maythen be introduced into the intervertebral space down an endoscopic tubeand seated in an appropriate position in the intervertebral disc space.

After the expandable fusion device 10 has been inserted into theappropriate position in the intervertebral disc space, the expandablefusion device 10 can then be expanded into the expanded configuration.As previously described, expansion of the anterior side 35 and posteriorside 40 may be independently controlled. For example, the anterior side35 and posterior side 40 may be separately expanded at different times,expanded at different rates, and/or expanded at the rate (e.g., tomaintain a desired lordotic angle θ). To expand the anterior side 35 ofthe expandable fusion device 10, the anterior ramped end 150 andanterior translation portion 140 may be moved with respect to oneanother. For example, the anterior ramped end 150 may be moved towardanterior translation portion 140 in direction indicated by arrow 165. Byway of further example, anterior translation portion 140 may be movedtoward anterior ramped end 150 in direction indicated by arrow 170. Orboth the anterior ramped end 150 and anterior translation portion 140may be moved toward one another. As the anterior ramped end 150 andanterior translation portion 140 move with respect to one another, theypush against the corresponding first anterior ramp frame 60 and secondanterior ramp frame 65, which in turn push against the first endplate 45and second endplate 50 to cause an increase in anterior height H_(a). Toexpand the posterior side 40 of the expandable fusion device 10, theposterior ramped end 155 and posterior translation portion 145 may bemoved with respect to one another. For example, the posterior ramped end155 may be moved toward posterior translation portion 145 in directionindicated by arrow 160. By way of further example, posterior translationportion 145 may be moved toward posterior ramped end 155 in directionindicated by arrow 175. Or both the posterior ramped end 155 andposterior translation portion 145 may be moved toward one another. Asthe posterior ramped end 155 and posterior translation portion 145 movewith respect to one another, they push against the corresponding firstposterior ramp frame 70 and second posterior ramp frame, which in turnpush against the first endplate 45 and second endplate 50 to cause anincrease in posterior height H_(p).

In the event the expandable fusion device 10 needs to be repositioned orrevised after being installed and expanded, the expandable fusion device10 can be contracted back to the unexpanded configuration, repositioned,and expanded again once the desired positioning is achieved. To contractthe expandable fusion device 10, the above-described procedure may bereversed. By way of example, for contraction of anterior side 35, theanterior ramped end 150 and anterior translation portion 140 may bemoved with away from one another using first actuation screw 75. Forcontraction of posterior side 40, the posterior ramped end 155 andposterior translation portion 145 may be moved with away from oneanother using second actuation screw 80.

First actuation screw 75 or another other suitable actuation mechanismmay be used to facilitate expansion of anterior side 35. As previouslydescribed, first actuation screw 75 may be disposed in bore 275 ofanterior ramped end 150 and bore 195 of anterior translation portion140. When first actuation screw 75 is rotated in a first direction, theanterior ramped end 150 and anterior translation portion may be drawncloser together. When first actuation screw 75 is rotated in a seconddirection (opposite the first direction), the anterior ramped end 150and anterior translation portion 140 may move away from one another.

Second actuation screw 80 or another other suitable actuation mechanismmay be used to facilitate expansion of posterior side 40. As previouslydescribed, second actuation screw 80 may be disposed in bore 290 ofposterior ramped end 155 and bore 225 of posterior translation portion145. When second actuation screw 80 is rotated in a first direction, theposterior ramped end 155 and posterior translation portion 145 may bedrawn closer together. When second actuation screw 80 is rotated in asecond direction (opposite the first direction), the posterior rampedend 155 and posterior translation portion 145 may move away from oneanother.

With reference now to FIGS. 7-11, an expandable fusion device 10 isshown according to another embodiment. As illustrated, the expandablefusion device 10 may comprise an anterior side 35 and a posterior side40. In the illustrated embodiment, the expandable fusion device 10comprises a pair of expandable implants, illustrated as anteriorexpandable implant 300 and posterior expandable implant 305,respectively. The anterior expandable implant 300 comprise a pair ofopposing anterior endplates 310 and the posterior expandable implant 305comprises a pair of opposing posterior endplates 315. The anteriorendplates 310 and the posterior endplates 315 may be expandedindependently allowing control of height on each side of expandablefusion device 10. The resultant lordotic angle θ may be based on thedifference in height between the anterior expandable implant 300 and theposterior expandable implant 305. The anterior expandable implant 300may be secured to the posterior expandable implant 305. By way ofexample, a connecting bar 320 may attach the anterior expandable implant300 to the posterior expandable implant 305.

FIG. 9 illustrates a front end view of expandable fusion device 10 withanterior endplates 310 expanded. As illustrated, the anterior expandableimplant 300 and posterior expandable implant 305 may share a front (ordriving) ramp 325. Bores 330 and 335 may be formed in front ramp 325through which first actuation screw 75 and second actuation screw 80 maybe disposed. Anterior expandable implant 300 may be expanded by rotationof first actuation screw 75, and posterior expandable implant 305 may beexpanded by rotation of second actuation screw 80. As the firstactuation screw 75 rotates, anterior ramps (not shown) may be drawn tofront ramp 325, while anterior ramps and front ramp 325 engage anteriorendplates 310 causing expansion of anterior expandable implant 300. Asthe second actuation screw 80 rotates, posterior ramps (not shown) maybe drawn to front ramp 325, while posterior ramps and front ramp 325engage posterior endplates 315 to cause expansion of posteriorexpandable implant 305. Front ramp 325 may further comprise a graft hole340. As illustrated, graft hole 340 may be disposed between bores 330and 335. Graft hole 340 may be sized to receive bone graft or similarbone growth inducing material and further allow the bone graft orsimilar bone growth inducing material to be packed in a central opening(not shown) of the expandable fusion device 10.

FIG. 10 illustrates a top view of expandable fusion device 10 withanterior endplates 310 expanded. As illustrated, connecting bar 320 maysecure anterior expandable implant 300 and posterior expandable implant305. In some embodiments, connecting bar 320 may be rigidly attached tonose 345 of posterior expandable implant 305. The connecting bar 320 maybe housed within a center shaft 350 on anterior expandable implant 300and may translate as anterior expandable implant 300 may be expanded orcollapsed.

Any suitable technique may be used for expansion of anterior expandableimplant 300 and posterior expandable implant 305. One technique forexpansion of anterior expandable implant and posterior expandableimplant 305 may be provided in U.S. Patent Publication No. 2014/0067071,the disclosure of which in incorporated herein by reference. While notillustrated, the anterior expandable implant 300 and posteriorexpandable implant 305 may each comprise a central ramp. The centralramps may include ramps that engage anterior endplates 310 and theposterior endplates 315. For expansion of anterior side 35, the firstactuation screw 75 may be rotated to draw the central ramp of theanterior expandable implant 300 and the front (or driving) ramp 325closer together, for example, by pulling the central ramp toward thefront ramp 325. The central ramp and front ramp 325 may engage theanterior endplates 310 forcing them apart. While not shown the centralramp and front ramp 325 may comprise ramps that engage correspondingramps in the anterior endplates 310. For expansion of posterior side 40,the second actuation screw 80 may be rotated to draw the central ramp ofthe posterior expandable implant 305 and the front (or driving) ramp 325closer together, for example, by pulling the central ramp toward thefront ramp 325. The central ramp and front ramp 325 may engage theposterior endplates 315 forcing them apart. While not shown the centralramp and front ramp 325 may comprise ramps that engage correspondingramps in the posterior endplates 315.

While the preceding description provides discusses techniques tofacilitate expansion it should be understood that the present disclosureshould not be limited to these techniques. Any suitable technique forfacilitating independent expansion of anterior side 35 and posteriorside 40 of expandable fusion device 10 may be used. The followingdescription of FIGS. 11-54 provide alternative expansion techniques thatmay be used to facilitate expansion of an anterior side 35 and posteriorside 40 of an expandable fusion device.

Referring now to FIG. 11, expandable fusion device 10 is shown accordingto another embodiment. In the illustrated embodiment, expandable fusiondevice 10 comprises first endplate 45 and second endplate 50. Asillustrated, the expandable fusion device 10 may further comprise anactuation screw 355 coupled to a ball bearing 360. The actuation screw355 and ball bearing 360 may be disposed between the first endplate 45and the second endplate 50. Rotation of actuation screw 355 would in inturn drive ball bearing 360. The ball bearing 360 may be moved back andforth between the first endplate 45 and second endplate 50 to adjustheight. The first endplate 45 and second endplate 50 may be coupled tohinges 365. As height of the expandable fusion device 10 may beadjusted, the first endplate 45 and second endplate 50 may pivot athinges 365. While not shown, the hinges 365 may be fixed to a frame.

FIG. 12 illustrates expandable fusion device 10 according to anotherembodiment. As illustrated, expandable fusion device 10 may comprisefirst endplate 45 and second endplate 50. The expandable fusion device10 may further comprise a frame 370. The frame 370 may have walls thatare angled, tapered, or otherwise formed. In the illustrated embodiment,the first endplate 45 and second endplate 50 may each have lips 375 thatmay overlap frame 370 and thereby prevent the first endplate 45 andsecond endplate 50 from dislocating. The first endplate 45 and secondendplate 50 may move freely within the frame 370, allowing theexpandable fusion device 10 to expand or contract while the firstendplate 45 and second endplate 50 may conform to anatomy of theadjacent vertebral bodies 15 and 20.

FIGS. 13-15 illustrate expandable fusion device 10 according to anotherembodiment. FIG. 14 is a cross-sectional view of FIG. 13 taken alongline a-a. FIG. 15 is a cross-sectional view of FIG. 13 taken along lineb-b. In the illustrated embodiment, expandable fusion device 10 maycomprise a first endplate 45 and a second endplate 50. Expandable fusiondevice 10 may further comprise a rear plate 380 through which a firstactuation screw 75 and a second actuation screw 80 may be disposed.First actuation screw 75 may be coupled to a first actuation ramp 385.Second actuation screw 80 may be coupled to a second actuation ramp 390.Ramped portions 395 may also be coupled to the first endplate 45 andsecond endplate 50. First actuation screw 75 may be rotated to drivefirst actuation ramp 385 to push ramped portion 395, which in turn maypush first endplate 45 to cause it to move outward on anterior side 35.Second actuation screw 80 may be rotated to drive second actuation ramp390 to push ramped portion 395, which in turn may push first endplate 45to cause to move outward on posterior side 40. In this manner, expansionon anterior side 35 and posterior side 40 may be independentlycontrolled. FIGS. 16a, 16b , and 17 illustrate the second endplate 50pivotally attached to ramped portion 395. FIG. 18 illustrates secondendplate 50 and ramped portion 395. Ramped portion 395 may be coupled tosecond endplate 50 to form an endplate assembly.

FIGS. 19-21 illustrate expandable fusion device 10 according to anotherembodiment. FIG. 20 is a cross-sectional view of FIG. 19 taken alongline c-c. FIG. 21 is a cross-sectional view of FIG. 20 taken along lined-d. As illustrated, the first actuation screw 75 and second actuationscrew 80 may be disposed through rear plate 380. First actuation screw75 and second actuation screw 80 may engage first shim 400 and secondshim 405, respectively. First shim 400 and second shim 405 may engage afirst pivot assembly 410 and second pivot assembly 415. First pivotassembly 410 and second pivot assembly 415 may pivot at first pivotpoint 420 and second pivot point 425, respectively. In the illustratedembodiment, first pivot assembly 410 and second pivot assembly 415 mayeach comprise pivot arms 416 coupled at first pivot point 420 and secondpivot point 425, respectively. First actuation screw 75 may be rotatedto cause first shim 400 to move in the direction of arrow 430 on FIG.20. First shim 400 may engage first pivot assembly 410 pushing it tocause first pivot assembly 410 to move outward in direction indicated byarrow 435. First pivot assembly 410 may lengthen as it moves outward,which in turn pushes on first endplate 45 and second endplate 50 causingthem to move away from one another, thus expanding on anterior side 35.Second actuation screw 80 may be rotated to cause second shim 405 tomove in the direction of arrow 430 on FIG. 20. Second shim 405 mayengage second pivot assembly 415 pushing it to cause second pivotassembly 415 to move outward in the direction of arrow 440. Second pivotassembly 415 may lengthen as it moves outward, which in turn pushes onfirst endplate 45 and second endplate 50 causing them to move away fromone another, thus expanding on posterior side 40.

FIGS. 22 and 23 illustrate expandable fusion device 10 according toanother embodiment. As illustrated, expandable fusion device 10 maycomprise first endplate 45 and second endplate 50. Cam member 450 may bedisposed between first endplate 45 and second endplate 50. Cam member450 may engage first endplate 45 and second endplate 50. Cam member 450may be rotatable. In some embodiments, cam member 450 may be rotated toadjust the angle between first endplate 45 and second endplate 50. FIG.23 illustrates expandable fusion device 10 after rotation of cam member450 to adjust the angle between the first endplate and the secondendplate 50 in accordance with present embodiments.

FIGS. 24 and 25 illustrate expandable fusion device 10 according toanother embodiment. As illustrated, expandable fusion device 10 maycomprise first endplate 45 and second endplate 50. A first cam member455 and a second cam member 460 may be disposed between first endplate45 and second endplate 50. First cam member 455 and second cam member460 may each engage first endplate 45 and second endplate 50. First cammember 455 and second cam member 460 may each be rotatable. In someembodiments, first cam member 455 may be rotated to force first endplate45 and second endplate 50 away from one another causing expansion onanterior side 35. In some embodiments, second cam member 460 may berotated to force first endplate 45 and second endplate 50 away from oneanother causing expansion on posterior side 40. Expandable fusion device10 may further comprise a linking plate 465 securing first endplate 45to second endplate 50. FIG. 24 illustrates expandable fusion device 10in a collapsed configuration. FIG. 25 illustrates expandable fusiondevice 10 in an expanded configuration after rotation of first cammember 455 and second cam member 460.

FIG. 26 illustrates another expansion technique that may be used toactivate expansion of an expandable fusion device 10 (e.g., shown onFIG. 1) in accordance with present embodiments. As illustrated, acentral bar 470 may be disposed between endplate connectors 476, whichmay be coupled to corresponding endplates (e.g., first endplate 45 andsecond endplate 50 on FIG. 1). Central bar 470 may be moved to differentlocations between endplate connectors 476. Depending on positioning ofcentral bar 470 between endplate connectors 476, there may be variableexpansion of the endplates.

FIGS. 27-29 illustrate another expansion technique that may be used toactivate expansion of an expandable fusion device 10 (e.g., shown onFIG. 1) in accordance with present embodiments. For simplicity, onlyfirst endplate 45 is shown on FIGS. 27-29. Anterior wedge 475 may bepositioned on anterior side 35 and may engage first endplate 45. Forexpansion on anterior side 35, anterior wedge 475 may be pushed intofirst endplate 45 from anterior side 35. As illustrated, anterior wedge475 may engage a corresponding ramped surface 480 on first endplate 45to push first endplate 45 outward causing expansion on anterior side 35.Posterior wedge 485 may be positioned on posterior side 40 and may alsoengage first endplate 45. For expansion on posterior side 40, posteriorwedge 485 may be pushed into first endplate 45 from posterior side 40.As illustrated, posterior wedge 485 may engage a corresponding rampedsurface 488 on first endplate 45 to push first endplate outward causingexpansion on posterior side 40. In some embodiments, anterior wedge 475and posterior wedge 485 may be pushed into first endplate 45 in adirection generally transverse to a longitudinal axis of the expandablefusion device.

FIGS. 30-33 illustrate expansion of a corpectomy device 490 according tosome embodiments. As illustrated on FIG. 30, corpectomy device 490 maycomprise a first cutting endplate 495 and a second cutting endplate 500.First cutting endplate 495 and second cutting endplate 500 may beoperable to cut away vertebral bodies. A cam member 505 may be disposedbetween first cutting endplate 495 and second cutting endplate 500.Rotation of cam member 505 may force first cutting endplate 495 andsecond cutting endplate 500 away from one another causing expansion ofcorpectomy device 490. FIG. 31 illustrates corpectomy device 490disposed between adjacent vertebral bodies 15 and 20. Cam member 505 maybe rotated to adjust the angel between the first cutting endplate 495and second cutting endplate 500, as shown on FIG. 32. In someembodiments, corpectomy device 490 may be used to remove adjacentvertebral bodies 15 and 20 and then expanded to engage additionalvertebral bodies 510 and 515, as shown on FIG. 33.

FIGS. 34 and 35 illustrate another expansion technique that may be usedto activate expansion of an expandable fusion device 10 (e.g., shown onFIG. 1) in accordance with present embodiments. FIG. 34 iscross-sectional side view of an expandable fusion device 10 takenthrough anterior side 35 in accordance with present embodiments. Asillustrated, on FIG. 35 an anterior ramped translation member 520 may bedisposed between first endplate 45 and second endplate 50. Anteriorramped translation member 520 may be disposed on anterior side 35 (e.g.,shown on FIG. 1) of expandable fusion device 10. Anterior rampedtranslation member 520 may comprise a plurality of ramped portions 525,which may engage corresponding ramped portions 530 in the first endplate45 and second endplate 50. Anterior ramped translation member 520 may bemoved such that ramped portions 525 in engage ramped portions 530 tocause first endplate 45 and second endplate 50 to move away from oneanother. FIG. 35 is a cross-sectional end view of an expandable fusiondevice 10 in accordance with present embodiments. Anterior rampedtranslation member 520 is shown between first endplate 45 and secondendplate 50. A linkage assembly 535 may engage anterior rampedtranslation member 520. Linkage assembly 535 may comprise a central arm540 that engages anterior ramped translation member 520 and extensionarms 545. Extensions arms 545 may be engaged to first endplate 45 andsecond endplate 50 on posterior side 40 at pivot points 550 for anteriorexpansion. In some embodiments, linkage assembly 535 may be drivenposteriorly to increase posterior height H_(p). In some embodiments,first endplate 45 and second endplate 50 may comprise one or alternatepivot points 555. By setting extension arms 545 in alternative pivotpoints 555, for example, the relationship between anterior height H_(a),posterior height H_(p), and lordotic angle θ may be adjusted.

FIGS. 36 and 37 illustrate expandable fusion device 10 according toanother embodiment. As illustrated, expandable fusion device 10 maycomprise upper anterior endplate 560 and upper posterior endplate 565.For simplicity, the lower endplates are not shown in the embodimentillustrated on FIGS. 36 and 37. As illustrated, expandable fusion device10 may further comprise frame 570. A first arm 575 may be coupled toupper anterior endplate 560 and frame 570. First arm 575 may pivot atconnection point 580 with frame and also pivot at connection point 585with upper anterior endplate 560. First rack lever 590 may also bepivotally coupled to upper anterior endplate 560 at connection point585. First rack lever 590 and a second rack lever 600 may be pivotallycoupled to frame 570 at a connection point 595. Second rack lever 600may be pivotally coupled to upper posterior endplate 565 at connectionpoint 605. A second arm 610 may be coupled to upper posterior endplate565 at connection point 605 and may also be coupled to frame 570 atconnection point 615. Second arm 610 may pivot at connection point 615with frame and also pivot at connection point 605 with upper posteriorendplate 565. For expansion on anterior side 35, a gear member (notshown) may engage first rack lever 590 and then be rotated, thus causinganterior side 35 to raise, as shown on FIG. 37. For expansion onposterior side 40, a gear member (not shown) may engage second racklever 600 and then be rotated, thus causing posterior side 40 to raise.

FIGS. 38 and 39 illustrate expandable fusion device 10 according toanother embodiment. As illustrated, expandable fusion device 10 maycomprise a first endplate 45 and a second endplate 50. A pair ofinternal arms 616 and 620 may be disposed between first endplate 45 andsecond endplate 50, wherein each of internal arms 616 and 620 engage thefirst endplate 45 and the second endplate 50. Internal arms 616 and 620may be coupled to different endplates on opposite sides of theexpandable fusion device 10. For example, internal arm 615 may becoupled to first endplate 45 on anterior side 35, while internal arm 620may be coupled to second endplate 50 on posterior side 40. Rotation ofthe internal arms 616 and 620 about their respective connection pointspushes the first endplate 45 and second endplate 50 apart, resulting inan increase in height. As each of the internal arms 616 and 620 isconnected at a different side of the expandable fusion device 10,internal arms 616 and 620 may be independently rotated allowing forindependent expansion of anterior side 35 and posterior side 40. Any ofa variety of suitable techniques may be used for rotation of internalarms 616 and 620. By way of example, the internals arms 616 and 620 maybe directly rotated at their respective connection points to the firstendplate 45 and second endplate 50. Another rotation technique mayinclude moving one of the internal arms 616 and 620 outward manuallywhere it meets the endplate but is not connected to the endplate.

FIG. 40 illustrates expandable fusion device 10 according to anotherembodiment. In the illustrated embodiment, expandable fusion device 10may comprise independently adjustable anterior and posterior endplates,such as upper anterior endplates 625 and upper posterior endplates 630.The endplates, such as upper anterior endplates 625 and upper posteriorendplates 630, may have independent expansion mechanisms so facilitateindependent expansion on anterior side 35 and posterior side 40. In someembodiments, expansion of upper anterior endplate 625 may be actuated byfirst actuation screw 75 and upper posterior endplate 630 may beactuated by second actuation screw 80.

FIGS. 41 to 45 illustrate expandable fusion device 10 according toanother embodiment. The illustrated embodiment is similar to theembodiment of FIG. 40 except expansion may be facilitated through asingle hole 635. FIG. 41 is a perspective view of the expandable fusiondevice 10 in accordance with present embodiments. FIG. 42 is across-sectional view of expandable fusion device 10 taken along plane 42of FIG. 41, in accordance with present embodiments. As illustrated,expandable fusion device 10 may comprise a posterior ramped translationmember 640 and an anterior ramped translation member 645. Implant driver650, which may include an elongated shaft, may be disposed in hole 635,for example, with a threaded connection. Implant driver 650 may be movedforward or backwards to drive the translation member (e.g., posteriorramped translation member 640, anterior ramped translation member 645,or both) and, thus, push the endplates apart causing expansion. Distalend 655 of implant driver 650 may rotate to engage posterior rampedtranslation member 640, anterior ramped translation member 645, or both.FIG. 43 illustrates engagement of distal end 655 with posterior rampedtranslation member 640 in accordance with present embodiments. FIG. 44illustrates engagement of distal end 655 with anterior rampedtranslation member 645 in accordance with present embodiments. FIG. 45illustrates engagement of distal end 655 with both posterior rampedtranslation member 640 and anterior ramped translation member 645 inaccordance with present embodiments.

FIG. 46 illustrates another technique for expansion of an expandablefusion device 10, for example, shown on FIG. 40 comprising a separatelyexpandable anterior and posterior endplates arranged side by side. Inthe illustrated embodiment, a lordotic screw 660 may extend through rearplate 680 to engage posterior ramped translation member 640. Asillustrated anterior ramped translation member 645 may comprise anextension 670 that is configured to engage a contact surface 665 ofposterior ramped translation member 640. Lordotic angle θ may be set byrotating lordotic screw 660 to push posterior ramped translation member640 and, thus, move contact surface 665 away from extension 670.Expansion screw 675 may be disposed through rear plate 680 to engageanterior ramped translation member 640. Expansion screw 675 may driveanterior ramped translation member 645 causing it to push againstcorresponding endplates (e.g., upper anterior endplates 625 and upperposterior endplates 630 on FIG. 40) moving them outward to therebyincrease anterior height H_(a). Anterior height H_(a) may first beadjusted to a desired height greater than posterior height H_(p) andthen extension 670 may engage contact surface 665 such that anteriorramped translation member 645 pushed posterior ramped translation member640 causing posterior ramped translation member 640 to push againstcorresponding endplates (e.g., upper anterior endplates 625 and upperposterior endplates 630 on FIG. 40) moving them outward to thereby alsoincrease posterior height H_(p). In some embodiments (not illustrated),the expandable fusion device 10 may first rock into a desired lordosisand then utilize ramps to expand the expandable fusion device 10.

FIGS. 47-49 illustrate another technique for expansion of an expandablefusion device 10, for example, shown on FIG. 1. In the illustratedembodiment, a ramped translation member 685 may be disposed betweenfirst endplate 45 and second endplate 50. Ramped translation member 685may be in the general shape of spheroid, which may be oblate or prolate,for example. Ramped translation member 685 may be driven between thefirst endplate 45 and second endplate 50 to drive them apart to increaseheight. Lordosis may be achieved passively, in some embodiments, byallowing the first endplate 45 and/or the second endplate 50 to rock onthe ramped translation member 685, as seen on FIG. 49. The firstendplate 45 and second endplate 50 may contour to the lordosis of thedisc space.

FIGS. 50-54 illustrate another technique for expansion of an expandablefusion device 10, for example, shown on FIG. 1. In the illustratedembodiment, an actuation frame 690 may comprise actuation screws 695that drive ramps 700 disposed in the actuation frame 690. Asillustrated, actuation frame 690 may comprise a proximal end 705 and adistal end 710, which may be tapered to facilitate insertion into thedisc space, for example. Lateral sides 715 may couple the proximal end705 and distal end 710. Ramps 700 may be disposed in lateral sides.Actuation screws 695 may be disposed in proximal end 705. As illustratedon FIG. 50, the ramps 700 may be at least partially retracted intoactuation frame 690. Rotation of actuation screws 695 may extend ramps700 from actuation frame 690, as seen in FIG. 51. FIGS. 52-54 are endviews showing independent expansion of ramps on anterior side 35 andposterior side 40. FIG. 52 illustrates ramps 700 at least partiallyretracted in actuation frame 690. Actuation screw 695 on anterior side35 may be rotated to cause ramps 700 on anterior side 35 to extend fromactuation frame 690, as seen on FIG. 53. While not shown ramps 700 onanterior side 35 may engage endplates (e.g., first endplate 45, secondendplate 50 on FIG. 2) to cause an increase in anterior height H_(a).Actuation screw 695 on anterior side 35 may be rotated to cause ramps700 on anterior side 35 to extend from actuation frame 690, as seen onFIG. 54. While not shown ramps 700 on anterior side 35 may engageendplates (e.g., first endplate 45, second endplate 50 on FIG. 2) tocause an increase in posterior height H_(p).

FIGS. 55A-62B illustrate an exemplary embodiment consistent with theprinciples of the present disclosure. With reference now to FIG. 55A-C,an exemplary embodiment of an expandable fusion device 5500 is shown.Expandable fusion device 5500 may include a first endplate 5502, asecond endplate 5504, and a translation member assembly 5506.Translation member assembly 5506 may further include anterior front ramp5508, anterior back ramp 5510, posterior front ramp 5512, and posteriorback ramp 5514. Device 5500 may also include joists 5516, 5518, 5520,and 5522. While reference to ramps 5508, 5510, 5512, and 5514 has beenmade according to the relative location within a patient afterimplantation, it should be noted that expandable fusion device 5500 maybe implanted in a different orientation (for example, in a positionupside down from the position as illustrated) thereby changing therelative anterior and posterior positions after implantation. Therefore,the position of ramps inside a patient is not limited and can beapplicable to both anterior and posterior positions.

FIGS. 55A-55D and FIGS. 56A-D show device 5500 in different states ofexpansion and angled arrangements. FIGS. 55A and 56A illustrate device5500 in a state of compression, which may be the state of implant uponinitial insertion into adjacent vertebral bodies within a patient. Thisstate of compression may be at a height of 7 mm but may also be otherheights depending upon the particular circumstances of the surgicalprocedure and/or the target vertebral bodies. FIGS. 55B and 56B showdevice 5500 in a state of partial expansion wherein the first posteriorramp 5512 and second posterior ramp 5514 are moved by translation member5506 in order to expand first endplate 5502 and second endplate 5504 onthe posterior side, while keeping the anterior side in a compressedposition or a position that is not as expanded as the posterior side, tocreate the shown angled arrangement of device 5500. FIGS. 55C and 56Cshow device 5500 in another angled arrangement, wherein translationmember 5506 moves first anterior ramp 5508 and second anterior ramp 5510in a manner resulting in first endplate 5502 and second endplate 5504 toexpand on the anterior side while keeping the posterior side unexpandedor less expanded than the anterior side. FIG. 56C additionallyillustrates joists 5520 and 5522 which are on the opposite side ofjoists 5516 and 5518. In FIG. 55D, device 5505 is shown in a state offull expansion wherein both the anterior and posterior sides areexpanded by translation member 5506 by moving ramps 5508, 5510, 5512,and 5514. As shown in FIGS. 55A-56D, expansion device 5500 may beexpanded to a desired posterior height and lordotic angle independent ofeach other as translation member 5506 may independently translate theanterior ramps 5508, 5510 (which move joists 5516 and 5518) and/ortranslate the posterior ramps 5512 and 5514 (which move joists 5520 and5522).

FIGS. 57A and 57B illustrate device 5500 in a state of lordoticexpansion wherein an anterior side 5524 of device 5500 is expanded whilea posterior side 5526 remains in a compressed configuration. FIG. 57Aillustrates device 5500 from the perspective of anterior front ramp 5508and posterior front ramp 5512, which may be the end that is initiallyinserted into adjacent vertebral bodies. FIG. 57B illustrates device5500 from the perspective of anterior back ramp 5510 and posterior backramp 5512, which may be the end accessible to a surgeon afterimplantation of device 5500. In addition to elements that have alreadybeen explained, FIG. 57A illustrates front bores 5528 and 5530 and graftwindow 5540. FIG. 57B illustrates back bores 5532 and 5534, internalposterior bore 5536, and graft window 5540. In operation, device 5500would be inserted (in a compressed state such as FIG. 55A) into a spacebetween adjacent vertebral bodies with front ramps 5508 and 5512 beingthe leading end. After insertion, it may be determined that expansion ofthe anterior side of device 5500 is appropriate. This may be effected byinserting a tool into back bore 5532 and engaging a screw (not shown)disposed in translation member 5506 at a location that causes anteriorfront ramp 5508 to move closer to anterior back ramp 5510. This in turncauses joists 5516, 5518 to move along translation member 5506 to expandthe anterior side 5524 of the device 5505 by separating first endplate5502 and the second endplate 5504 from a compressed position. Once adesired position is reached, the screw is locked in place therebysecuring the position of the endplates in the desired orientation.Because back bores 5532 and 5534 are open, graft material may bedelivered to device 5500 through one or both of bores 5532 and 5534 intotranslation member 5506 which may then flow out of graft window 5540.The creates a manner in which to backfill device 5500 with graftmaterial after implantation. The operation of translation member 5506,joists 5516, 5518, 5520, 5526, endplates 5502 and 5504 are explained ingreater detail below.

FIGS. 58A-58B illustrate an exemplary embodiment of translation member5506 that may be used in expansion fusion device 5500. In addition tocomponents previously described, translation member 5506 may includeanterior translation bar 5542, posterior translation bar 5544, ramps5546, posterior translation component 5548, anterior translationcomponent 5550, posterior screw or actuation member 5552, anterior screwor actuation member 5554, anterior interior bore 5556. In an exemplaryoperation, anterior translation bar 5542 may be connected to joists 5516and 5518, which in turn may be connected to an anterior side of firstendplate 5502 and second endplate 5504.

Movement of device 5500 in order to expand the endplates 5502 and/or5504 may be done by a mechanical mechanism that allows for the front andback ramps to slide towards each other and lock in position once adesired expansion has been achieved. For example, in order to expand onthe anterior side, anterior translation bar 5542 may be engaged byinserting a tool through back bore 5536 to engage screw 5554 disposed inanterior internal bore 5556 and connected to front bore 5528. By turningscrew 5554, anterior front ramp 5508 may be moved closer to anteriortranslation component 5550. Joists 5516 and 5518 that are connected tothe anterior translation bar 5542 slide along ramps 5546 on the anteriorside via corresponding ramps disposed on joints 5516 and 5518 to expandendplates 5502 and 5504 from the compressed position. The orientationmay be locked once the desired expansion has been achieved.

FIG. 58B illustrates a top view of translation member 5506, whereinposterior translation bar 5544 is moved closer to posterior front ramp5512. This would have the effect of moving corresponding joists 5520,5522 to expand the posterior side of endplates 5502 and 5504.

Referring to FIGS. 59-61B, FIG. 59 illustrates an exemplary embodimentof translation member 5506 connected to joists 5516, 5518, 5520, and5522. Due to the perspective of FIG. 59, joist 5522 is not shown. FIG.60 shows two exemplary types of joists. FIG. 61A-61B show an exemplaryembodiment of either endplate 5502 or 5504 and the manner it may engagethe two types of joists illustrated in FIG. 60.

Joists 5516, 5518, 5520, and 5522 may contain separate componentsconfigured to engage endplates 5502, 5504 using different types ofattachment mechanisms and may contain ramps that engage translationmember 5506. For example, FIG. 60 illustrates a first type of joist 6002and a second type of joist 6004. Joist 6002 may contain pockets 6006 andjoist 6004 may contain a cylindrical bore 6008. The joists may alsocontain ramps 6010 configured to engage corresponding ramps 5546.Previously mentioned joists 5516, 5518, 5520, and 5520 may be eithertype of joist.

In exemplary embodiments, the joists may be disposed such that a topside of device 5500 contains one type of joist (for example, joist 6002)on one side of the device (either anterior or posterior) and the othertype of joist (for example, joist 6004) on the other side of the device.As shown in FIG. 59, joist 5516 may have cylindrical bore 6008 and joist5520 may have pockets 6006. Pockets 6006 may be configured to engagetabs 6102 disposed on an underside of one of the endplates. For example,FIG. 61A shows the underside of endplate 5502 with tabs 6102 disposed onone side and a cylindrical stem 6104 disposed on the other side that isconfigured to engage cylindrical bore 6008. As shown in FIG. 61B,endplate 5502 may be configured to be disposed on joists 5516 and 5520using this type of engagement. Fully assembled, device 5500 would appearas illustrated in FIGS. 55A-55D.

Cylindrical stem 6104 and cylindrical bore 6008 may provide a set pointfrom each of endplates 5502, 5504 may pivot. Tabs 6102 may be configuredsuch that they pivot inside the respective pockets 6006 and/or slidetowards the opposing side of device 5500. This migration, howeverslight, may allow endplates 5502 and 5504 to articulate while device5500 is at a fixed width.

FIGS. 62A-63 show an exemplary embodiment of a translation member 6200consistent with the principles of the present disclosure. Translationmember 6200 is similar to other translation members discussed herein.Translation member 6200 may contain a locking stem 6202 which may bedisposed therein. Locking stem 6202 may comprise internal teeth 6208 andcounter-torque tabs 6210.

Teeth 6208 and tabs 6210 may engage a tool that is inserted into opening6206 of translation member 6200 in order to provide a rigid connectionbetween locking stem 6202 and the tool. The tool may then be used tomanipulate translation member 6200 to ultimately expand a fusion devicecontaining translation member 6200. In operation, while the tool isengaged with locking stem 6202 and is manually drawn towards opening6206, the fusion device may expand due to endplates secured totranslation member 6200 as otherwise provided herein, for example, usingjoists discussed above. When moved in a direction away from opening6206, the fusion device may move to a more compressed state. In order tofix the position of the desired expansion or compression, locking stem6202 may be locked by rotating locking stem 6202, for example, byrotating the locking stem by 90°. Upon this rotation, external teeth6212 of locking stem 6202 may engage with internal teeth inside internalramps 6214 of translation member 6200 (shown in FIG. 63) to lock device6200 in a desired orientation.

Turning now to FIGS. 64A-68D, one embodiment of expandable fusion device5500 is shown in more detail. Implant 5500 may be inserted at a reducedheight and offers the surgeon independent control over the lordoticangle and posterior height of the implant 5500. The implant 5500 isconfigured to utilize independent expansion mechanisms on the anteriorand posterior sides 5524, 5526 of the implant 5500. Both anteriorexpansion and posterior expansion of the implant 5500 may be controlledseparately which allow the surgeon to dial in the desired amount ofposterior height and lordotic angle. If desired, expansion may also beperformed simultaneously on both sides of the implant 5500 in order topreserve the current lordotic angle of the implant 5500 and only changethe posterior height.

FIGS. 64A-64B show front views of the front ramps 5508, 5512 and theendplates 5502, 5504 in collapsed and expanded positions, respectively.FIG. 64B shows the implant 5500 partially expanded to an arbitraryangle. The posterior side 5526 has height X mm and the anterior side5524 has height Y mm based on the given amount of expansion. In thisembodiment, anterior height Y is greater than posterior height X toachieve the desired overall height and lordosis. The expansionmechanisms 5506 are controlled independently of each other which allowthe implant 5500 to be expanded to the desired posterior height andlordotic angle independent of each other.

As best seen in FIGS. 65A-65B, the expansion mechanism of the implant5500 includes opposing wedges or ramps 5508, 5510, 5512, 5514 with ramps5546, 5558 on both the anterior and posterior sides 5524, 5526 of theimplant 5550. The front ramps 5508, 5512 oppose the series of back ramps5510, 5514. Anterior front ramp 5508 and anterior back ramp 5510 createanterior expansion and posterior front ramp 5512 and posterior back ramp5514 create posterior expansion. As these ramps 5508, 5510, 5512, 5514are drawn together, the movement forces four joists 5516, 5518, 5520,5522 (shown in FIG. 65B) to expand vertically via the ramps 5508, 5510,5512, 5514. As front ramps 5508, 5512 and back ramps 5510, 5514 aredrawn together, the movement causes the implant 5500 to expandvertically. Expansion of the implant 5500 is caused by the opposingramps 5508, 5510, 5512, 5514 sliding towards each other. The fourcomponents 5508, 5510, 5512, 5514 are configured to slide in thedirections indicated by the arrows in FIG. 65A. FIG. 65B shows theimplant 5500 fully expanded on the anterior and posterior sides 5524,5526.

With emphasis on FIGS. 66A-66B, expansion of the implant 5500 occurs asthe front ramps 5508, 5512 and back ramps 5510, 5514 are drawn towardseach other. This movement can be achieved by one or more mechanicalmechanisms that allows the ramps 5508, 5510, 5512, 5514 to slide towardseach other and lock them in place after the implant 5500 has beenexpanded to a desirable orientation. In one embodiment, the implant 5500is expanded utilizing a pair of actuation members 5552, 5554, such asscrews. Posterior screw 5552 is positioned through opening 5536 inposterior translation component 5548 and into front bore 5530 in theposterior front ramp 5512. Similarly, anterior screw 5554 is positionedthrough opening 5556 in anterior translation component 5550 and intofront bore 5528 in the anterior front ramp 5508. Rotation of the screws5552, 5554 is configured to draw the front ramps 5508, 5512 and the backramps 5510, 5514 together. One screw 5554 expands the anterior side 5524while the other screw 5552 expands the posterior side 5526 of theimplant 5500.

Turning now to FIGS. 67A-67D, the endplates 5502, 5504 are configured topivot on top of the respective joists 5516, 5518, 5520, 5522. FIGS.67A-67D depict upper endplate 5502 and two representative joists 6002,6004 but it will be appreciated that the same configuration may beapplied to lower endplate 5504. The endplate 5502 includes an inner orunderside 6106 configured to contact and interface with the joists 6002,6604 and an opposite outer side 6108 configured to engage bone. Theouter side 6108 of the endplate 5502 may include a plurality of teeth,ridges, or other friction enhancing surfaces for engaging bone. Theinner or under side 6106 of the endplate 5502 may define a longcylindrical stem 6104 that engages with the cylindrical bore 6008 injoist 6002. The long cylindrical stem 6104 may extend from the front tothe back of the endplate 5502 along almost its entire length. Thecylindrical stem 6104 may have a hollow body throughout its length. Theopposite side of the endplate 5502 may include one or more tabs 6102that sit inside corresponding pockets 6006 on joist 6004. For example, apair of tabs 6102 may be positioned near the respective front and rearends of the endplate 5502. The cylindrical stem 6104 and bore 6008provide a set point from which the endplate 5502 pivots. The tabs 6102not only pivot inside their respective pockets 6006 but tabs 6102 alsoslide towards the opposing side of the implant 5500. Although veryslight, the migration of the tabs 6102 allows the endplate 5502 tosuccessfully articulate all while the implant 5500 remains at a fixedwidth.

Turning now to FIGS. 68A-68B, the expanded endplates 5502, 5504 ofimplant 5500 are shown from front and rear perspectives, respectively.As the front and rear ramp components 5508, 5510, 5512, 5514 are drawntowards each other via actuation members 5552, 5554, expansion of theendplates 5502, 5504 occurs in a vertical direction. The difference inheight on each side 5524, 5526 of the implant 5500 creates the angle ofthe implant 5500. The endplates 5502, 5504 pivot on the joists 5516,5518, 5520, 5522 as the implant expands. The expansion on the posteriorside 5526 of the implant 5500 controls the posterior height, while theexpansion on the anterior side 5524 of the implant 5500 drives thelordotic angle. The resultant angle of the implant 5500 is based on thedifference in height between the anterior and posterior sides 5524, 5526of the implant 5500. Independent control of lordotic angle and posteriorheight may allow the surgeon to better customize the shape and fit ofthe implant 5500 to the patient anatomy. A tailored fit may help reducethe risk of subsidence and provide overall better post-surgical resultsfor the patient.

In order to ensure the height and lordosis of the implant 5500 remain inposition, one or more additional locking mechanisms may be built intothe design of the actuation members 5552, 5554. These mechanisms may bepassive or active requiring a secondary locking step. With reference toFIGS. 69A-69D, one such configuration of a passive locking mechanism isshown. Although generally described with reference to actuation member5552, it will be appreciated that the locking mechanism is equallyapplicable to actuation member 5554.

As best seen in FIG. 69A, each actuation member 5552, 5554 includes ahead 5560 and a shaft 5562 extending along a central longitudinal axisthat terminates at a distal end 5564. The head 5560 is configured to bereceived in the respective bores 5536, 5556 in the translationcomponents 5548, 5550 and the shaft 5562 is configured to be received inthe respective bores 5528, 5530 in the front ramps 5508, 5512. The shaft5562 may be threaded along its length and is configured to threadedlyengage the respective threaded bores 5528, 5530 in the front ramps 5508,5512. The head 5560 may include a collar 5566 receivable in acorresponding recess in the respective openings 5536, 5556 in thetranslation components 5548, 5550, thereby securing it therein. The head5560 may define an instrument driving recess 5568 configured to receivean instrument, such as a driver, to thereby rotate the actuation member5552, 5554. The instrument recess 5568 may include a torx, hex, or othersuitable driving recess for engagement by the instrument. The head 5560defines a plurality of protrusions 5570 with gaps therebetween extendingradially around the screw head 5560 and a channel 5572 below theprotrusions 5570.

A secondary locking washer 5580 may be both keyed to the implant body toprevent its own rotation, and spans the protrusions 5570 on the screwhead itself. As best seen in FIG. 69B, the locking washer 5580 mayinclude a full ring 5582 connected to a partial ring 5584 by an arm5586. As best seen in FIG. 69D, the full ring 5582 of the locking washer5580 may have an offset or asymmetric face configured to cover the topof the head 5560. The partial ring 5584 is configured to seat within thechannel 5572 in the head 5560 of the actuation member 5552, 5554. Asshown in FIGS. 69A and 69C, the arm 5586 is configured to seat within agap between two adjacent protrusions 5570 along the head 5560. The arm5586 may form a projection 5588 from the outer periphery of the fullring 5582, which is configured to interface with an implant key 5590.The implant key 5590 may define a recess and/or slidable or flexible tabconfigured to engage with the projection 5588. When the projection 5588is seated into the recess and engaged with the tab of the implant key5590, the actuation member 5552, 5554 is locked in position. Wheninserting a driver to rotate the actuation member 5552, 5554, thelocking washer 5580 is pulled aside, releasing the actuation member5552, 5554 to rotate freely. Removing the driver allows the lockingwasher 5580 to key into the protrusions 5570 on the screw head 5560,limiting its rotation. Alternatively, a secondary locking washer may beadded as a final step or may be used to provide friction against theactuation member 5552, 5554 instead of a keyed mechanism.

FIGS. 70A-70B illustrate an instrument 5600 that may be used to insertand/or expand the implant 5500. The instrument includes a body 5602 withan attached handle at the proximal end for controlling the instrument5600. The distal end of the body 5602 may include a pair of tabs 5604configured to interface with corresponding instrument notches 5606 onopposite sides of the back ramps 5510, 5514 of the implant 5500.

Given the two through-apertures 5532, 5534 located on the proximal endof the implant 5500, multiple instrumentation options may be used towork with the implant 5500 to aid in insertion, removal, graft packing,etc. One such example includes a threaded configuration on either orboth sides of the implant 5500, thereby allowing for a robust connectionduring insertion. In one embodiment, the body 5602 of the instrument5600 may receive a cannulated shaft or sleeve 5608 with a threaded end5610 configured to interface with one of the back bores 5532, 5534 ofthe back ramps 5510, 5514. One driver 5612 may be positioned throughsleeve 5608. The distal tip 5614 of the driver 5612 is configured toengage with the drive recess 5568 in the head 5560 of the actuationmember 5552, 5554. When torque is applied to the driver 5612, theactuation member 5552, 5554 is rotated, thereby expanding the endplates5502, 5504.

A second driver 5612 may be positioned through the other rear bore 5532,5534 and into the drive recess 5568 of the other actuation member 5552,5554. The two drivers 5612 may be generally aligned in parallel with oneanother. When the drivers 5612 are engaged with the respective actuationmembers 5552, 5554, the actuation members 5552, 5554 may be rotated tothereby expand the endplates 5502, 5504 of the implant 5500. Thecannulated shafts or sleeve(s) 5608 may allow for manipulation ofactuation member(s) 5552, 5554 during insertion, and while the inserter5600 remains attached to the implant 5500.

The rear apertures 5532, 5534 also provide for the ability to introducegraft material into the device 5500, both during insertion with theimplant 5500 remaining connected to the insertion instrumentation 5600,or by accessing either aperture 5532, 5534 directly with noinstrumentation attached. Other instrumentation could also be used toallow for angled access for difficult to reach disc spaces, tools to aidin removal and/or repositioning, and/or tools designed to monitor theimplants position via computer-aided visual tracking and/or navigation.

Turning now to FIGS. 71A-73, alternative embodiments ofthree-dimensional (3D) printed endplates 5700 are shown. The implantsand components thereof may be machined, constructed from additivemanufacturing, such as three-dimensional (3D) printing, subtractivemanufacturing, or hybrid manufacturing processes. 3D printing may offerdifferent surface topology patterns in order to provide a favorablesurface for bone on-growth as well as aid in implant strength. In orderto provide an implant with structural rigidity at a reduced height, itmay be favorable to create a balance between implant structure and areasof porosity to aid in spinal fusion.

The 3D printed endplates 5700 may utilize one or more surface patternsconfigured to promote bone growth. Each endplate 5700 includes a frontside 5702, an opposite back side 5704, an anterior side 5706 and anopposite posterior side 5708. The front side 5702 of the endplate 5700may define a bump out or projection configured to fit in a correspondingrecess in the top of the front ramps 5508, 5512 when unexpanded.Similarly, the back side 5704 may define a bump out or projectionconfigured to fit in a corresponding recess in the top of the rear ramps5510, 5514 when unexpanded. The anterior and posterior sides 5706, 5708may be thickened or enlarged along their lengths to increase thestructural support along the sides of the endplate 5700. A window 5710through the endplate 5700 may be defined by an inner wall 5712. Thewindow 5710 may be configured to form part of and align with the graftwindow 5540 through the implant 5500. The inner wall 5712 may includeone or more notches 5714 pointed toward the anterior and/or posteriorsides 5706, 5708. The notches 5714 may be configured to receive theramps 5546 on the respective anterior and posterior translation bars5542, 5544.

With emphasis on FIGS. 71A-71C, the endplate 5700 may include ahexagonal pattern 5720 according to one embodiment. The hexagonalpattern 5720 may be comprised of a plurality of open hexagonal frames.The open hexagonal frames may form a repeating pattern filling inbetween the outer walls 5702, 5704, 5706, 5708 and inner wall 5712 ofthe endplate 5700. The hexagonal units may be open on the top andunderside of the endplate 5700. As best seen in the side view in FIG.71C, the tops of the hexagonal pattern 5720 may define a plurality ofbi-directional teeth 5722 configured to engage bone. The hexagonalpattern 5702 allows the implant 5500 to be printed with less materialwhile still targeting structural rigidity comparable to endplatescreated with conventional machining practices. The hexagonal pattern5720 integrates with the bi-directional endplate teeth 5722 all whilefollowing the bi-convexity curves of the endplate profile.

With emphasis on FIGS. 72A-72C, the endplate 5700 may include a strutpattern 5730 according to one embodiment. The strut pattern 5730 may becomprised of a plurality of parallel struts. The strut pattern 5730 mayrun perpendicular along the length of the endplate 5700. The struts maybe equally spaced between the front and the back ends 5702, 5704 of theendplate 5700. The struts may extend between the anterior and posteriorwalls 5706, 5708 or between the outer wall 5706, 5708 and the inner wall5712 of the endplate 5700. The struts may be open on the top andunderside of the endplate 5700. A central frame 5734 may be providedbetween some of the struts to further improve the structural integrityof the endplate 5700. Similar to pattern 5720, the tops of the strutsmay define a plurality of bi-directional teeth 5732 configured to engagebone. The struts may integrate with the bi-directional endplate teeth5732 all while following the bi-convexity curves of the endplateprofile.

With emphasis on FIGS. 73, alternative embodiment of endplates 5700 areshown. Endplate 5700A depicts a solid 3D printed endplate with aplurality of pyramidal teeth configured to engage bone. The 3D printedendplates 5700B, 5700C show a porous lattice structure 5740 configuredto provide a structurally rigid endplate with open ends of porosity toact as a channel for tissue through growth. The porous lattice structure5740 may include any suitable structure, unit cells, pore size, and/orporosity. Endplate 5700B depicts a 3D printed endplate with the strutpattern 5730 filled in with the porous lattice structure 5740. The areasbetween the struts on the top and underside of the endplate 5700B areprinted with the porous lattice structure 5740 to provide a conduit fortissue growth through the spacer. Similarly, endplate 5700C depicts a 3Dprinted endplate with the hexagonal pattern 5720 filled in with theporous lattice structure 5740. The hex endplate 5700C may also beprinted with the porous lattice structure 5740 in order to provide anadditional conduit for tissue growth.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims. Althoughindividual embodiments are discussed, the invention covers allcombinations of all those embodiments.

What is claimed is:
 1. An expandable fusion device comprising: first and second endplates; a plurality of moveable joists engaged with the first and second endplates; a translation member assembly including an actuation member and a plurality of ramps engaged with the plurality of joists; and a locking washer keyed to the actuation member, wherein the actuation member is configured to move the joists such that the first and second endplates move away from one another, and the locking washer is configured to prevent rotation of the actuation member, thereby locking a height and lordosis of the first and second endplates.
 2. The expandable fusion device of claim 1, wherein the actuation member includes a head and a threaded shaft extending along a central longitudinal axis that terminates at a distal end.
 3. The expandable fusion device of claim 2, wherein the translation member assembly includes a translation component defining a first through bore and a front ramp defining a second through bore, wherein the head of the actuation member is receivable through the first bore in the translation component and the shaft is receivable through the second bore in the front ramp.
 4. The expandable fusion device of claim 2, wherein the head defines a plurality of protrusions with gaps therebetween extending radially around the head and a channel below the protrusions.
 5. The expandable fusion device of claim 4, wherein when inserting a driver to rotate the actuation member, the locking washer is pulled aside, releasing the actuation member to rotate freely, and removing the driver allows the locking washer to key into the protrusions on the head, thereby limiting rotation of the actuation member.
 6. The expandable fusion device of claim 4, wherein the locking washer includes a full ring connected to a partial ring by an arm, wherein the full ring is configured to rest against a top of the head, the partial ring is configured to seat in the channel, and the arm is configured to fit within one of the gaps between the protrusions along the head.
 7. The expandable fusion device of claim 6, wherein the arm forms a projection from an outer periphery of the full ring, wherein the projection is configured to interface with an implant key defining a recess and a tab configured to engage with the projection.
 8. The expandable fusion device of claim 6, wherein the full ring has an asymmetric face configured to cover the top of the head.
 9. An expandable fusion device comprising: first and second endplates; first and second joists engaged with the first endplate; third and fourth joists engaged with the second endplate; a translation member in engagement with the first, second, third, and fourth joists; a first actuation member in engagement with the translation member, wherein the first actuation member is configured to move the first and third joists to expand the first and second endplates on a first side of the expandable fusion device; a first locking washer attached to the first actuation member, wherein the first locking washer is configured to prevent rotation of the first actuation member; a second actuation member in engagement with the translation member, wherein the second actuation member is configured to move the second and fourth joists to expand the first and second endplates on a second side of the expandable fusion device; and a second locking washer attached to the second actuation member, wherein the second locking washer is configured to prevent rotation of the second actuation member.
 10. The expandable fusion device of claim 9, wherein the first side is an anterior side and the second side is a posterior side, and wherein the first actuation member expands the anterior side while the second actuation member expands the posterior side.
 11. The expandable fusion device of claim 9, wherein the first and second endplates are configured to pivot on top of the respective joists.
 12. The expandable fusion device of claim 9, wherein one of the joists comprises a pocket configured to receive a tab disposed on the first or second endplate, and wherein another joist comprises a cylindrical bore configured to receive a cylindrical stem disposed on an opposite side of the first or second endplate.
 13. The expandable fusion device of claim 12, wherein the cylindrical stem is hollow and extends from a front toward a back of the first or second endplate.
 14. The expandable fusion device of claim 9, wherein one or both of the first and second endplates are 3D printed with a surface pattern and bi-directional teeth configured to promote bone growth.
 15. The expandable fusion device of claim 14, wherein the surface pattern is a hexagonal pattern filled with a porous lattice structure.
 16. The expandable fusion device of claim 14, wherein the surface pattern is a parallel strut pattern filled with a porous lattice structure.
 17. A system for installing and/or expanding an expandable fusion device, the system comprising: an expandable fusion device comprising: first and second endplates; a translation member assembly disposed at least partially between the first and second endplates, wherein the translation member assembly comprises: an anterior translation component disposed on an anterior side of the expandable fusion device including an anterior back ramp with a first through bore; an anterior actuation member including a head and a threaded shaft for moving the anterior translation component; a posterior translation component disposed on a posterior side of the expandable fusion device including a posterior back ramp with a second through bore; and a posterior actuation member including a head and a threaded shaft for moving the posterior translation component, wherein rotation of the anterior and/or posterior actuation members is configured to expand the fusion device on the anterior side and/or posterior side, respectively, to achieve a height and lordosis of the first and second endplates; and an instrument for installing and/or expanding the expandable fusion device comprising: a body with a cannulated sleeve attachable to one of the first and second through bores; a first driver positionable through the cannulated sleeve, the first driver having a tip configured to engage with a drive recess in the head of the anterior or posterior actuation member; and a second driver having a tip configured to engage with a drive recess in the head of the other actuation member.
 18. The system of claim 17, wherein a distal end of the body includes a pair of tabs configured to interface with corresponding instrument notches on opposite sides of the anterior and posterior back ramps.
 19. The system of claim 17, wherein the first and second drivers are aligned in parallel.
 20. The system of claim 17, wherein the first or second through bore is internally threaded and the cannulated sleeve has a threaded end configured to mate with the internally threaded bore of the anterior or posterior back ramp. 